The present invention relates to an aggregate for feeding fuel from a supply tank to an internal combustion engine of a motor vehicle.
More particularly, it relates to an aggregate of the above mentioned type which has a feed pump with a rotatable driven feeding element arranged in a pump chamber and feeding fuel from a suction opening of the pump chamber to a pressure opening of the pump chamber, wherein in at least one of two chamber end walls in the region of a sealing surface an opening which leads to an unloading chamber is provided.
Feeding aggregates of the above mentioned general type are known in the art. One of such feeding aggregates is disclosed for example in the German document DE-A 40 20 520. This feeding aggregate has a feed pump which is formed as a flow pump and has a rotatable driven feeding element formed as a vane wheel arranged in a pump chamber. By the vane wheel, fuel during the operation of the feed pump is transported from a suction opening which opens into the pump chamber to a pressure opening which leads from the pump chamber. In a chamber end wall which limits the pump chamber an opening is formed in the region of a sealing surface near the pressure opening so as to communicate the pump chamber with a region of the system in which the low pressure acts. The opening is formed by an unloading passage and an opening which leads from the unloading passage. Gas bubbles which flow back to the suction opening from the pressure opening due to gaps provided between the vane wheel and the chamber end wall are withdrawn through this opening. Otherwise, their suction by the vane wheel disturbs the operation of the feeding aggregate. Due to the arrangement of the unloading passage near the pressure opening, only those gas bubbles are discharged in it which are produced in the region of the pressure opening. Gas bubbles which are produced between the unloading passage and the suction opening can flow back to the suction opening and disturb the operation of the feeding aggregate.